Strict radiation reference levels shunned to stem Fukushima exodus

May 25, 2013

By SHINICHI SEKINE/ Staff Writer

The government avoided setting stringent radiation reference levels for the return of Fukushima evacuees for fear of triggering a population drain and being hit by ballooning costs for compensation, an Asahi Shimbun investigation shows.

The revelation could rekindle debate over the government’s safety standards as many evacuees prepare for their eventual return. They were displaced by the nuclear disaster more than two years ago.

In December 2011, the government led by the Democratic Party of Japan decided to lift the evacuation order for areas with residual doses of up to 20 millisieverts per year.

The government was regrouping areas in Fukushima Prefecture to pave the way for the return of some evacuees based on radiation doses as of November that year.

But minutes of ministerial meetings and accounts by meeting participants show that government officials initially sought a 5-millisievert cutoff line to ensure evacuees’ safety.

The number was later eased to 20 millisieverts as some Cabinet members insisted on responding to local officials’ concern that the tougher yardstick could spur population flight. They also factored in the possibility that costs of compensation for evacuees could significantly rise if they were unable to return home in the contaminated areas for a prolonged period.

The proposal for an annual radiation dose of 5 millisieverts was floated at an unofficial meeting of ministers concerned on Oct. 17, 2011, about seven months after the nuclear disaster unfolded at the Fukushima No. 1 nuclear power plant.

Goshi Hosono, the minister in charge of the nuclear disaster, insisted on that figure at the meeting. Industry minister Yukio Edano and Tatsuo Hirano, the reconstruction minister, were among other government officials present.

Hosono argued that a 5-millisievert yardstick is appropriate because there is a wide gap between 20 millisieverts, on which the government’s initial evacuation order was based, and 1 millisievert, the goal the government set to declare contaminated areas safe after cleanup efforts, according to the minutes.

When the government set a planned evacuation zone outside the 20-kilometer no-entry zone around the crippled plant right after the disaster unfolded, it adopted the 20-millisievert cutoff line.

It is the toughest of the 20-100 millisieverts per year range set for the emergency phase in the 2007 recommendation by the International Commission on Radiological Protection (ICRP).

Five years after the 1986 Chernobyl accident, a dose of 5 millisieverts was used as criteria for relocating residents for safety reasons.

In Japan, a site measuring more than 5.2 millisieverts per year is designated as a radiation controlled area.

There has been a case of a Japanese worker who developed leukemia after having an equivalent dose of radiation while working at a nuclear power plant being recognized as patient of work-related illness.

With these factors in mind, the ministers agreed on setting the safety limit around 5 millisieverts at the meeting.

But at a meeting on Oct. 28, joined by Chief Cabinet Secretary Osamu Fujimura and Tatsuo Kawabata, internal affairs minister, participants appeared reluctant to approve a yardstick other than 20 millisieverts.

It apparently reflected their concern that the 5-millisievert standard could lead to a surge in evacuees as parts of the prefectural capital of Fukushima and Koriyama, a major city, come under this category.

The areas falling in the range of 5 millisieverts represented 13 percent of the land space of the prefecture.

“The prefectural government could not function with population drain under the 5-millisievert scenario,” said a state minister who attended the meeting. “In addition, there were concerns that more compensation money will be needed, with an increase in the number of evacuees.”

At the meeting on Nov. 4, the participants informally settled on the 20-millisievert proposal, saying it is difficult to draw a clear line between 1 millisievert and 20 millisieverts.

The current government is working toward the return of evacuees based on this policy.

One of the participants acknowledged that the 20-millisievert proposal was lax, while the 1-millisievert idea would result in the pullout of all the residents in the prefecture.

“So we weighed the 5-milliseivert yardstick, but we could not settle on it due to the argument that it would raise the number of evacuees,” said the official.

The DPJ government produced a report in December 2011 that the 20-millisievert cutoff line would be appropriate despite some experts’ objections to it.

Although the DPJ government emphasized safety, it did not explain that government officials arrived at the figure after giving consideration to a potential rise in the number of evacuees under the 5-millisievert scenario.

The Abe administration in March decided to release by the end of this year a set of protection measures for evacuees returning to areas with doses of up to 20 millisieverts.

The move is apparently aimed at setting the stage for return of evacuees even if decontamination operation fails to achieve the target of 1 millisievert.

In fact, many local governments admitted that cleanup efforts have yet to produce the intended results.

Fukushima Prefecture Governor Yuhei Sato has suggested the target of 1 millisievert is not realistic.

It will be difficult to attain the goal of “zero evacuees in 2020” as things stand today.

But critics say the central and local governments will come under fire for putting priority on the return of evacuees over their safety.

By SHINICHI SEKINE/ Staff Writer
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An official closes a barrier at an access point to the "Difficult-to-return zone" in Okuma, Fukushima Prefecture. (Asahi Shimbun file photo)

An official closes a barrier at an access point to the "Difficult-to-return zone" in Okuma, Fukushima Prefecture. (Asahi Shimbun file photo)

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  • An official closes a barrier at an access point to the "Difficult-to-return zone" in Okuma, Fukushima Prefecture. (Asahi Shimbun file photo)
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